Hyaluronic acid (HA) is a macromolecular chain polysaccharide consisting of regularly repetitive disaccharide units of D-glucuronate and N-acetylaminoglucose, having a molecular weight ranging from several thousands to several millions. HA has good lubricity, viscoelasticity, and non-immunogenicity and is highly moisturizing. At present, commercially available HA is extracted from animals or prepared from bacterial fermentation, and is used mainly as sodium salt in clinical therapy (such as in opthalmology, orthopedics, dermatology, in prevention of postoperative adhesion, etc.) and in cosmetics. The preparation and use of potassium, calcium, magnesium, aluminum, ammonium, silver and gold salts of hyaluronate have been disclosed in many patents. Hyaluronic acid forms salts (complexes) with ions of Group III metals from the 4th period in the periodic table of elements, such as zinc hyaluronate and cobalt hyaluronate, which have been proved to have therapeutic effect on skin ulcers and bedsore (WO9010020). Zinc hyaluronate also possesses significant stomach-protecting activity, and is useful in preventing and treating peptic ulcer (CN1126548). However, bismuth hyaluronate (a complex) and its preparation and use have never been reported in literature.
Gastrointestinal disorders include chronic gastritis, peptic ulcer, functional dyspepsia, gastric cancer and the like, among which peptic ulcer has a high incidence and seriously impairs health of modern people. An epidemiologic investigation in China revealed that 10% of population suffers from this disease during their lifetime, with onset mostly seen in young and middle-aged people (people aging from 20 to 50 accounting for about 70%). The pathogenetic mechanism of peptic ulcer is complicated and not yet fully illuminated. The basic mechanism underlying peptic ulcer may be summarized as imbalance between injury to local GI mucous membrane (ulcerogenic factors) and protection of the mucous membrane (mucosal barrier). When the injury increases or the protection weakens, ulcers occur. Recently, it has been found that the development of peptic ulcer in human is associated with infection by Helicobacter pylori. 
Currently, the combined use of antibiotics, antacid and mucosa protecting agent is generally accepted as the optimal treatment for peptic ulcer, wherein the mucosa protecting agent is a film-forming, anti-acid substance that is capable of preventing the penetration of gastric acid and pepsin through the mucous membrane, including sucralfate, bismuth compounds, prostaglandin derivatives and the like. The bismuth compounds exhibit high affinities for sulfur, oxygen and nitrogen and strong binding to metallothionein, mucosal glycoproteins, enzyme and peptides. There is evidence indicating its effectiveness in inhibiting the growth of Helicobacter pylori. Therefore, bismuth agents are the most frequently used mucosa protecting agent in clinic, among which bismuth potassium citrate, bismuth subsalicylate, bismuth subnitrate, colloidal bismuth pectin and the like are commonly used. The pharmacological effect of bismuth agents may be generalized as follows: forming precipitates in the acid condition within the stomach; adhering to the surface of the gastric mucosa to form a protective layer; protecting the gastric mucosa (in ulcer areas); reducing adverse stimuli to the stomach; promoting the regeneration of ulcerous mucosa and the healing of the ulcer; modulating the secretory action, such as by reducing the activity of pepsin, increasing the secretion of mucoprotein, enhancing release of PGE2 by the mucosa; adsorbing bacteriocins (such as the toxin produced by Escherichia coli and the enterotoxin produced by Vibrio cholerae); and the direct antibacterial activity against the pathogenic microorganisms (Helicobacter pylori).
Biomacromolecular bismuth agents, such as colloidal bismuth pectin, show significantly better therapeutic effect in the treatment of diseases such as gastro-duodenal ulcer, chronic superficial gastritis, chronic atrophic gastritis, alimentary tract hemorrhage and the like than other small molecular ones due to their strong adhesion selectivity, i.e. the specific affinity to the area of gastrointestinal ulcer and the inflaming surface. HA is a biomacromolecular mucopolysaccharide naturally occurring in animal bodies, with no structural differences across species, and has good viscoelasticity, lubricity and film-forming ability. Studies show that HA is involved a number of cellular and physiological processes, such as cell migration and differentiation, wound healing, metastasis of cancer cells, effects on growth factors, embryogenesis and development and inflammation. HA has been experimentally proven to tend to directionally accumulate in sites of inflammation and injury, and macromolecular HA exerts anti-inflammatory activity by inhibiting the function of macrophages. In acid conditions, HA solution shows higher viscosity and formation of macromolecular network structure, and is gel like and strongly adhering. These properties of HA greatly contribute to the use of bismuth hyaluronate as a mucosa protecting agent. Animal experiments shown below demonstrate significantly higher inhibition of acetic acid and acidified ethanol-induced gastric ulcer by bismuth hyaluronate as compared with colloidal bismuth pectin in rats.